Submitted to: Arabidopsis Research International Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 5/28/2006
Publication Date: 6/28/2006
Citation: Li, L., Lu, S., O'Halloran, D. 2006. Or encodes a cysteine-rich zinc finger domain containing protein in regulating high-level of beta-carotene accumulation in cauliflower. Arabidopsis Research International Conference Proceedings. Paper No. 54.
Technical Abstract: The Or (Orange) mutant in cauliflower is a spontaneous, semi-dominant mutation that induces high level of B-carotene accumulation in various tissues of the plant. A single gene coding for Or has been identified using map-based cloning and successfully verified by phenotypic complementation in the wild type cauliflower and Arabidopsis ap1-1 cal-1 "cauliflower" mutant. Sequence analysis revealed that the mutation is due to a 4.7 kb insertion of a LTR retrotransponson in the Or allele, which results in alternative splicing. The Or gene encodes a plastid-associated protein containing a cysteine-rich zinc binding domain. The gene appears to be plant-specific. Homologs of the cauliflower Or gene were found in divergent plant species, including Arabidopsis, tomato, maize, and rice. Or is expressed highly in very young leaves, curds, and flowers. The tissue-specific expression was further confirmed by examining the expression of Proor:GUS in transgenic Arabidopsis plants. Subcellular location study revealed that OR-GFP targets to leucoplasts in the epidermal cells of young leaves and localized at the plastid division midpoint in developing seeds of transgenic Arabidopsis plants. Or likely functions in association with chromoplast differentiation for carotenoid accumulation and exerts additional control on plastid division.